I did the following tricky stuff with the existing hardware and the hardware which came with the HiFiBerry.

Now the way I’ve done this, using available hardware, the connector doesn’t fully bottom out on the GPIO pins on the board of the Raspberry Pi but it’s a more than adequate connection for operation, and it’s screwed down and not able to move upwards at all. Good enough, sez I.

This photo also provides a better view of the plastic posts and plastic nut holding the DAC board down.

And oh yeah, I use this Pi for Shairport streaming which makes it show up under iTunes as an Airplay device. I explain how to do that here

So there’s a lot of ways to do this but I installed cronie which is a cron job app (hey I’m old school) and set a cron to start shairport at reboot.

Note that the card number differs from the example on the other link just above.

@reboot shairport -a AirPiB+ -o alsa -- -d hw:0,0

Update:

The HiFiBerry DAC designed for the Raspberry Pi A and B versions also fits in a GeauxRobot case, although only the 3.5mm headphone jack version only will probably fit.